An infrared ray detecting element receives infrared rays which cause the infrared ray detecting element to generate heat, and thus raise the temperature of the infrared ray detecting element. The infrared ray detecting element detects a change in electrical property corresponding to the change in temperature. Infrared ray detecting elements include, for example, pyroelectric infrared ray detecting elements, resistance bolometer infrared ray detecting elements, and thermopile infrared ray detecting elements. An infrared ray detecting element, which uses pyroelectric substance material, detects infrared rays by utilizing the charge produced on its surface due to the temperature change. A resistance bolometer infrared ray detecting element, which uses a resistance bolometer material, detects infrared rays by utilizing resistance values which change due to the temperature change. A thermopile infrared ray detecting element detects infrared rays by utilizing the Seebeck effect in which thermoelectromotive force is produced by a temperature difference.
FIG. 11 is a top view schematically illustrating a conventional infrared ray detecting element 200. FIG. 12 is a cross-sectional view schematically illustrating cross-section 12-12 of the conventional infrared ray detecting element 200 in FIG. 11.
In the conventional infrared ray detecting element 200, an infrared ray detecting portion 120 has a detection layer 116 which receives infrared rays, a lower electrode layer 140, and an upper electrode layer 150. The detection layer 116 is sandwiched between the lower electrode layer 140 and the upper electrode layer 150. The infrared ray detecting portion 120 is fixed to a substrate 112 via four support portions provided in two diagonal lines. The infrared ray detecting portion 120 is disposed above a cavity 113 provided in the substrate 112.
Lead wiring patterns 170 and 171 for leading electrical signals from the infrared ray detecting portion 120 to the outside are provided on two support portions 130 and 131, respectively, which are provided in one of the diagonal lines. Lead wiring patterns 170 and 171 are connected, via external lead portions 160, to conductive vias 142 which penetrate through the substrate 112. An insulating layer 115 formed on the substrate 112, the lead wiring pattern 170 connected to the lower electrode layer 140, and an interlayer insulating film 141 are sequentially stacked in the support portion 130. Furthermore, the insulating layer 115, the interlayer insulating film 141, and the lead wiring pattern 171 connected to the upper electrode layer 150 are sequentially stacked in the support portion 131.
In this manner, the structure in which the infrared ray detecting portion 120 is separated from the substrate 112 is an insulating structure capable of preventing the heat of the infrared ray detecting portion 120 from diffusing to the substrate 112. As such, the infrared ray detecting element 200 can efficiently detect the heat in infrared ray detecting portion 120 which is generated when incident infrared rays are absorbed. With this, the infrared ray detecting element 200 is capable of enhancing infrared ray detection sensitivity.